1. Field of the Invention
The present invention relates to wireless communications, and more specifically, to a method and apparatus of a terminal transmitting and receiving a signal in a TDD (Time Division Duplex) system.
2. Related Art
3GPP (3rd Generation Partnership Project) TS (Technical Specification) Release-8-based LTE (long term evolution) is a prevailing next-generation mobile communication standard.
As disclosed in 3GPP TS 36.211 V8.7.0 (2009-05) “Evolved Universal Terrestrial Radio Access (E-UTRA); Physical Channels and Modulation (Release 8),” the physical channel in LTE may be divided into downlink channels, such as PDSCH (Physical Downlink Shared Channel) and PDCCH (Physical Downlink Control Channel), and uplink channels, such as PUSCH (Physical Uplink Shared Channel) and PUCCH (Physical Uplink Control Channel).
The PUCCH is an uplink control channel used for transmitting uplink control information such as HARQ (hybrid automatic repeat request) ACK/NACK (acknowledgement/not-acknowledgement) signal, CQI (Channel Quality Indicator), and SR (scheduling request).
Meanwhile, mobile communication systems include a TDD (Time Division Duplex) system and an FDD (frequency Division Duplex) system.
The TDD system uses the same frequency on both downlink and uplink, and the FDD system uses different frequencies on downlink and uplink, respectively.
Conventionally, a frame, in the TDD system, is configured to have an uplink subframe, a downlink subframe, and a special subframe through an upper layer signal. However, such scheme requires a high time delay in configuring or reconfiguring a subframe, and when traffic on downlink and uplink varies dynamically, this scheme thus has a difficulty in efficiently allocating resources.
Further, the TDD system, in case the subframes in the frame are configured in the order of a downlink subframe and an uplink subframe, needs a special subframe between the downlink subframe and the uplink subframe. A terminal sends out an uplink signal a TA (timing advanced) value earlier than a subframe boundary in the uplink subframe. Such uplink signal may act as interference in receiving a downlink signal. Accordingly, a special subframe including a time gap is disposed between the downlink subframe and the uplink subframe.
The TDD system needs a method of being able to prevent resource waste that may occur due to a special subframe while dynamically performing a configuration of subframes in a frame.